/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.client;

import java.io.IOException;
import java.net.URI;
import java.util.concurrent.TimeUnit;
import javax.net.ssl.SSLException;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelConfig;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.SocketChannelConfig;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.HttpClientCodec;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.handler.timeout.ReadTimeoutHandler;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.http.HttpMethod;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * {@link org.springframework.http.client.ClientHttpRequestFactory} implementation
 * that uses <a href="http://netty.io/">Netty 4</a> to create requests.
 *
 * <p>Allows to use a pre-configured {@link EventLoopGroup} instance: useful for
 * sharing across multiple clients.
 *
 * <p>Note that this implementation consistently closes the HTTP connection on each
 * request.
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @author Brian Clozel
 * @author Mark Paluch
 * @since 4.1.2
 * @deprecated as of Spring 5.0, in favor of
 * {@link org.springframework.http.client.reactive.ReactorClientHttpConnector}
 */
@Deprecated
public class Netty4ClientHttpRequestFactory implements ClientHttpRequestFactory,
        AsyncClientHttpRequestFactory, InitializingBean, DisposableBean {

    /**
     * The default maximum response size.
     *
     * @see #setMaxResponseSize(int)
     */
    public static final int DEFAULT_MAX_RESPONSE_SIZE = 1024 * 1024 * 10;


    private final EventLoopGroup eventLoopGroup;

    private final boolean defaultEventLoopGroup;

    private int maxResponseSize = DEFAULT_MAX_RESPONSE_SIZE;

    @Nullable
    private SslContext sslContext;

    private int connectTimeout = -1;

    private int readTimeout = -1;

    @Nullable
    private volatile Bootstrap bootstrap;


    /**
     * Create a new {@code Netty4ClientHttpRequestFactory} with a default
     * {@link NioEventLoopGroup}.
     */
    public Netty4ClientHttpRequestFactory() {
        int ioWorkerCount = Runtime.getRuntime().availableProcessors() * 2;
        this.eventLoopGroup = new NioEventLoopGroup(ioWorkerCount);
        this.defaultEventLoopGroup = true;
    }

    /**
     * Create a new {@code Netty4ClientHttpRequestFactory} with the given
     * {@link EventLoopGroup}.
     * <p><b>NOTE:</b> the given group will <strong>not</strong> be
     * {@linkplain EventLoopGroup#shutdownGracefully() shutdown} by this factory;
     * doing so becomes the responsibility of the caller.
     */
    public Netty4ClientHttpRequestFactory(EventLoopGroup eventLoopGroup) {
        Assert.notNull(eventLoopGroup, "EventLoopGroup must not be null");
        this.eventLoopGroup = eventLoopGroup;
        this.defaultEventLoopGroup = false;
    }


    /**
     * Set the default maximum response size.
     * <p>By default this is set to {@link #DEFAULT_MAX_RESPONSE_SIZE}.
     *
     * @see HttpObjectAggregator#HttpObjectAggregator(int)
     * @since 4.1.5
     */
    public void setMaxResponseSize(int maxResponseSize) {
        this.maxResponseSize = maxResponseSize;
    }

    /**
     * Set the SSL context. When configured it is used to create and insert an
     * {@link io.netty.handler.ssl.SslHandler} in the channel pipeline.
     * <p>A default client SslContext is configured if none has been provided.
     */
    public void setSslContext(SslContext sslContext) {
        this.sslContext = sslContext;
    }

    /**
     * Set the underlying connect timeout (in milliseconds).
     * A timeout value of 0 specifies an infinite timeout.
     *
     * @see ChannelConfig#setConnectTimeoutMillis(int)
     */
    public void setConnectTimeout(int connectTimeout) {
        this.connectTimeout = connectTimeout;
    }

    /**
     * Set the underlying URLConnection's read timeout (in milliseconds).
     * A timeout value of 0 specifies an infinite timeout.
     *
     * @see ReadTimeoutHandler
     */
    public void setReadTimeout(int readTimeout) {
        this.readTimeout = readTimeout;
    }


    @Override
    public void afterPropertiesSet() {
        if (this.sslContext == null) {
            this.sslContext = getDefaultClientSslContext();
        }
    }

    private SslContext getDefaultClientSslContext() {
        try {
            return SslContextBuilder.forClient().build();
        } catch (SSLException ex) {
            throw new IllegalStateException("Could not create default client SslContext", ex);
        }
    }


    @Override
    public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {
        return createRequestInternal(uri, httpMethod);
    }

    @Override
    public AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod) throws IOException {
        return createRequestInternal(uri, httpMethod);
    }

    private Netty4ClientHttpRequest createRequestInternal(URI uri, HttpMethod httpMethod) {
        return new Netty4ClientHttpRequest(getBootstrap(uri), uri, httpMethod);
    }

    private Bootstrap getBootstrap(URI uri) {
        boolean isSecure = (uri.getPort() == 443 || "https".equalsIgnoreCase(uri.getScheme()));
        if (isSecure) {
            return buildBootstrap(uri, true);
        } else {
            Bootstrap bootstrap = this.bootstrap;
            if (bootstrap == null) {
                bootstrap = buildBootstrap(uri, false);
                this.bootstrap = bootstrap;
            }
            return bootstrap;
        }
    }

    private Bootstrap buildBootstrap(URI uri, boolean isSecure) {
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(this.eventLoopGroup).channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel channel) throws Exception {
                        configureChannel(channel.config());
                        ChannelPipeline pipeline = channel.pipeline();
                        if (isSecure) {
                            Assert.notNull(sslContext, "sslContext should not be null");
                            pipeline.addLast(sslContext.newHandler(channel.alloc(), uri.getHost(), uri.getPort()));
                        }
                        pipeline.addLast(new HttpClientCodec());
                        pipeline.addLast(new HttpObjectAggregator(maxResponseSize));
                        if (readTimeout > 0) {
                            pipeline.addLast(new ReadTimeoutHandler(readTimeout,
                                    TimeUnit.MILLISECONDS));
                        }
                    }
                });
        return bootstrap;
    }

    /**
     * Template method for changing properties on the given {@link SocketChannelConfig}.
     * <p>The default implementation sets the connect timeout based on the set property.
     *
     * @param config the channel configuration
     */
    protected void configureChannel(SocketChannelConfig config) {
        if (this.connectTimeout >= 0) {
            config.setConnectTimeoutMillis(this.connectTimeout);
        }
    }


    @Override
    public void destroy() throws InterruptedException {
        if (this.defaultEventLoopGroup) {
            // Clean up the EventLoopGroup if we created it in the constructor
            this.eventLoopGroup.shutdownGracefully().sync();
        }
    }

}
